It wasn't immediately clear how Bagcheck fits in with Twitter's plans, but the company has gained some engineering talent through the deal: One of Bagcheck's co-founders, Sam Pullara, is a former chief technologist at Yahoo. He's now joining the engineering team at Twitter.
Bagcheck's service will remain operational, at least for now, but "as with any acquisition, things may change at some point in the future," Bagcheck said in a blog post.
Terms of the acquisition weren't disclosed, and Twitter didn't immediately respond to a request for comment. Bagcheck's other co-founder, Luke Wroblewski, who also previously worked at Yahoo, has left the company to work on "the next big thing."
In addition to letting people share and comment on each others' lists, Bagcheck has a commerce element: When people create their lists, or "bags," as Bagcheck calls them, each entry includes a link to an e-commerce website where other people can buy the same item.
Bagcheck is one of a handful of acquisitions Twitter has made this year. In May, it bought AdGrok, which makes software for managing Google AdWords campaigns, and in the same month it bought TweetDeck, the popular Twitter client.